Chute



f Aug, 1o, 1943. W L SWTH 2,326,504

CHUTE Filed July 3. 1941 ATTO R N EYS` m, vm

Patented Aug. 10, 1943 lnarran i sf'rar Wesley'L. Smith, .Bedford,;va.', assigner tofz'eat.` 'j A American Industries, nc., iNewjYork, N. Y., a

corporation of Delaware nppueauen .nay e, 1941 ,serial No'. 401,047

(ci. ies-s2) 2 Claims.

This invention relates to chutes ,and aimsA to provide 'an' improved lchute whose surface is adapted to retard the speedsat which materials ow along the chute.

In accordance with my invention, a chute is f provided with an upper surface consisting of a layer of soft, substantially solid rubber contain-V ing almostwholly collapsed, closed cells. Suchk rubber is made by expanding a mass of soft- ,rubber compound by means of a blowing agent such as sodium bicarbonate or the like under conditions which retain the gases produced by of compound, and thencooling the rubber mass after vulcanization. The cooling has the effect of condensing or otherwise eliminating the gases produced by the blowing agent sothat the soft vulcanized rubber collapses substantially to the volume which it had before expansion. In its collapsed form, it has about the same degree of resiliency and the same wearing qualities as solid unexpanded soft rubber. Such collapsed cell lular rubber has been made as anintermediate product in making sponge rubber, butit has generally been regarded as of no value in itself.

I have discovered that whengthe upper wear:- ing surface of a chute is made of a layer of collapsed cellular rubber, itis resilient, strongv and durable, and has the property of gripping on` smooth surfaces until it is completely Worn away, so that the angle of inclination of a chute designed for handling such materials may be increased but the speeds at which the materialsv flow down through such a chute are controlled to the desired limits. lThis property is due to the fact that wear on the outer surface of a chute having an upper layer of collapsed cellular rubber opens the collapsed cells at the wearing sur- Vthe blowing agent in closed cells within the `mass face, relieving the vacuum in those cells so that they expand and serve, by a vacuum-cup action, to prevent materials with smooth surfaces from slipping along the chute too rapidly. Thus, although the upper coating of the chute has only the normalresiliency 'of solid, soft rubber, its

outer surface, as wear continues,l consists always of a thin layer of expanded rubberpitted with open cells which serve Vas vacuum cups. To pro- Yvide the `desired upper surface for the coating of the chutewhen it is new, that' surface may be made with molded indentations which provide Van initial vacuum-cup action.

i A chute embodying my invention is illustrated in the accompanying drawing in which:

Fig. 1 is a fragmentary section of a chutev taken along the line l-l of Fig. 2; v

Fig. 2 is a, cross section of a chute taken along the line 2--2 in Fig. 1';

Fig. 3 is an enlarged fragmentary view of the section illustratedin Fig. 2; and Y Fig. 4 is a similar section illustrating the up-Z per surface of the chute after wear.-

The chute illustrated in the drawing comprises I a base 6 of metal, Wood, or other strong, rigid material coated witha layer l of-a1rnost wholly collapsed, closedcell cellular rubber. When the A' chute is new, the speed of ilow of materials along it is retarded bythe Vacuum-cupV action of lthe indentations 8 in the tough outerskin 9. After. wear, a like effect is occasioned by the vacuumcupaction ofthe open and Vexpanded cells Ill as shown in fl. The cellsfll in the body remain collapsed until they are `exposed by wear.

The surface coating l which has been described may be made by utilizing the first part ofthe method of making sponge rubber described-in United States Letters Patent No;2,297,018. This method consists in expanding a mass of rubber compound by sodium bicarbonate or a similar blowing agent Vwhich is mixed withfthe compound before vulcanization. During .the iirst partof the vulcanizatii'in,` the rubber compound is confined 'in a mold having an internal volume Y no greater than the volume of the compound.

This prevents any substantial evolution ofjga's within the rubber compound during the iir'stpart of the vulcanization and until therubberrv compound has acquired consistency and tensile f strength sufficient to Vprevent entrapped gas from',

rupturing it.` YDuring the latter partof 4the v'ulf canization, the lrubber compound is placed in a larger mold. On release yfrom therst mold, or-. during the final vulcanzation in the-larger. mold or at both these times, the mass., is expanded by gas produced kby the blowing'agent, so that;v at the end of the vulcanization, there is produceda shape and size of the second rnold.

closed-cell cellular soft rubber article having the l Since thegasproduced from sodium`bicarbonate or-similar blowingagents' is of an unstable character, the 'gas is condensed orin lsome Way. chemically eliminated from, the cells when the K expandedarticle is cooled, so that it collapses and returns nearly to'the `size whichthe compound had before expansion;

v Y In using this method to makea chutefembodyv ing my invention. the moldY used inthe firstpart' of the vulcanization has a thickness substantially equal to that desired in the coating layer 1 Y The 'second mold has a thickness several times as V great as thatrof the iirst mold, and most desir ably has one of its surfaces roughened to mold indentations in one surface of the rubber. The roughened surface of the mold may be a knurled metal surface or a piece of coarse fabric laid in the mold. The roughened surface of the mold has two effects: (l) it molds the indentations in the surface of the rubber and (2) it allows the gas trapped in the cells near the surface to escape, so that a tough, non-cellular outer skin 9 is produced. Y

The coating layer 1 may be attached with its roughened'surface exposed, to the base 6 by one of thek cements customarily used for cementing rubber to a surface of metal or of wood or the like.r I prefer to use one of the so-called coldA curing rubber cements for this purpose. A hot curing `15 indentations.

cement may be used, but in that case the chute must be enclosed in a mold which will prevent undue expansion during the curing of the cement.

What I claim is: v

1. A chute consisting of a rigid base Whose upper surface has attached theretoA a layer of soft, substantially solid rubber containing almost wholly collapsed closed cells and whose outer surface is pitted with vacuum cups. f t

2. A chute consisting of a rigid base whose upper surface has attached thereto a layer of soft, substantially solid rubber containing Y almost Wholly collapsed closed cells and having a tough outer skin Whose surface isptted with molded WESLEY L. SMITH. 

